Endocrine Physiology: Central Hormones Flashcards

1
Q

Endocrine system includes

A
Hypothalamus 
Pituitary 
Thyroid 
Parathyroid
Adrenals 
Pancreas 
Ovaries 
Testes
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2
Q

Chemical regulating system

A
Hormones = 
Made in glands or cells 
Transported by blood 
Distant target tissue receptors 
Activates physiological response
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3
Q

Hormone function

A

Control of = enzymatic reactions, transport of ions or molecules across cell membranes, gene expression and protein synthesis
Exert effects at very low concentrations
Bind to target cell receptors
Half-life indicates length of activity

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4
Q

Hormones control…

A
Water balance and blood volume 
Metabolism 
Energy balance and appetite 
Digestion 
Circulation 
Growth and development 
Reproduction 
RBC production 
Stress management
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5
Q

Tropic hormones

A

Act on other endocrine glands = control of hormone secretion
Non tropic hormones = act on effector organs

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6
Q

Hormones and neuropeptides

A

Endocrine glands =
Secrete hormones
Ductless

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7
Q

Neurohormones/neuropeptides

A

Neuro-secretory cells = secrete neurohormones or neuropeptides
Adrenal medulla = catecholamines
Hypothalamus = posterior pituitary

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8
Q

Hormones classification

A

Peptide hormones = protein
Steroid hormones = cholesterol
Amine hormones = tryptophan or tyrosine (amino acids)

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9
Q

Peptide or protein hormones

A

Prepohormone = large, inactive
Pro hormone = post-translational modification
Hormone = final cuts make before it exits the cell to make it an active hormone, travels freely in the blood but cannot cross cell membrane, short half-life

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10
Q

Peptide hormone-receptor complex

A

Surface receptor
Hormone binds = enzyme activation or opens channel or 2nd messenger systems
Cellular response

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11
Q

Steroid hormone features

A

Cholesterol derived = lipophilic and can enter target cell
Must travel in blood bound to a protein
Cytoplasmic or nuclear receptors (mostly) = activate DNA for protein synthesis
Slower acting
Longer half-life
Examples = cortisol, estrogen, testosterone

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12
Q

Amine hormone features

A

Ring structures
Derived from one of 2 amino acids
Tryptophan = melatonin
Tyrosine = thyroid hormones and catecholamines (epinephrine, norepinephrine, and dopamine)

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13
Q

Amine hormone structure

A

Catecholamines behave similar to peptides

Thyroid hormones behave similar to steroids

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14
Q

Synthesis and storage: peptide hormones

A

Made in advance

Stored in secretory vesicles

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15
Q

Synthesis and storage: steroid hormones

A

Synthesized on demand from precursors

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16
Q

Synthesis and storage: catecholamines

A

Made in advance

Stored in secretory vesicles

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17
Q

Synthesis and storage: thyroid hormones

A

Made in advance

Precursor stored in secretory vesicles

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18
Q

Release from parent cell: peptide hormones

A

Exocytosis

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19
Q

Release from parent cell: steroid hormones

A

Simple diffusion

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20
Q

Release from parent cell: catecholamines

A

Exocytosis

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21
Q

Release from parent cell: thyroid hormones

A

Simple diffusion

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22
Q

Transport in blood: peptide hormones

A

Dissolved in plasma

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23
Q

Transport in blood: steroid hormones

A

Bound to carrier proteins

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24
Q

Transport in blood: catecholamines

A

Dissolved in plasma

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25
Transport in blood: thyroid hormones
Bound to carrier proteins
26
Half-life: peptide hormones
Short
27
Half-life: steroid hormones
Long
28
Half-life: catecholamines
Short
29
Half-life: thyroid hormones
Long
30
Location of receptor: peptide hormones
Cell membrane
31
Location of receptor: steroid hormones
Cytoplasm our nucleus | Some have membrane receptors also
32
Location of receptor: catecholamines
Cell membrane
33
Location of receptor: thyroid hormones
Nucleus
34
Response to receptor-ligand binding: peptide hormones
Activation of second messenger systems | May activate genes
35
Response to receptor-ligand binding: steroid hormones
Activation of genes for transcription and translation | May have nongenomic actions
36
Response to receptor-ligand binding: catecholamines
Activation of second messenger systems
37
Response to receptor-ligand binding: thyroid hormones
Activation of genes for transcription and translation
38
General target response: peptide hormones
Modification of existing proteins and induction of new protein synthesis
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General target response: steroid hormones
Induction of new protein synthesis
40
General target response: catecholamines
Modification of existing proteins
41
General target response: thyroid hormones
Induction of new protein synthesis
42
Examples of peptide hormones
Insulin | Parathyroid hormone
43
Examples of steroid hormones
Estrogen Androgens Cortisol
44
Example of catecholamine proteins
Epinephrine | Norepinephrine
45
Example of thyroid hormone
Thyroxine (T4)
46
Blood hormone levels depend on
Rate of hormone secretion Rate of hormone degradation Rate of hormone excretion (kidneys)
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Hormone interactions
``` Synergism = multiple stimuli (more than additive) eg) glucagon, epinephrine, cortisol Permissiveness = need second hormone to get full expression Anatgonsim = pairs of hormones with opposing effects eg) glucagon opposes insulin ```
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Examples of permissiveness
One sided effect TH increases number of receptor sites and increases effect of epinephrine But epinephrine does not necessarily increase effect of TH
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Negative feedback
Self regulates hormone levels | Turns off response homeostatically
50
Endocrine control
3 levels Hypothalamic (from CNS) Pituitary stimulation (hypothalamic tropic hormones) Endocrine glands stimulation (pituitary tropic hormones)
51
Other factors
``` Hormone secretion also affected by: Emotional state Disease state Stress Diet Sleep Body cycles (cardiac rhythm, menstrual cycle) ```
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Endocrine dysfunction
Abnormal plasma concentrations of a hormone Hyposecretion = too little hormone is secreted Hypersecretion = too much hormone is secreted
53
Hyposecretion
Primary hyposecretion = too little hormone is secreted due to gland abnormality Causes = genetic (type 1 diabetes), dietary (iodine and TH), chemical or toxic, immunologic/auto-immune (hashimotos), diseases/cancer Secondary hyposecretion = gland is normal but too little hormone is secreted due to decreased tropic hormone (anterior pituitary)
54
Hypersecretion
Causes = tumours (can continuously secrete excess hormone), immunologic Primary hypersecretion = too much hormone is secreted due to abnormality within gland Secondary hypersecretion = excessive stimulation from outside the gland causes over secretion
55
Hypothalamus
Homeostasis | Controls anterior pituitary which then controls other endocrine glands
56
Hypothalamic releasing and inhibiting hormones
Anterior pituitary hormones are stimulated or inhibited by one or more hypothalamic hormones
57
Posterior pituitary (neurohypophyis)
Hormones made in the hypothalamus Oxytocin and ADH Stored in the posterior pituitary When neuron is excited hormone is released
58
Oxytocin
Stimulates uterine contractions in child birth | Promotes milk ejection during lactation
59
ADH (vasopressin)
Anti-diuretic hormone Released if blood volume is low or blood osmolarity is high (eg-dehydration) Increases water reabsorption in kidney (decreases urine output)
60
Diabetes insipidus
Decreased ADH Excessive polyuria (urinating 8-90L of urine in 24 hours, hypotension, dizziness, constipation) Treated with vasopressin replacements
61
Anterior pituitary (adenohypophysis)
``` Secretes 6 peptide hormones 5 are tropic FSH LH Growth hormone TSH Prolactin ACTH ```
62
Gonadotropins
``` FSH = follicle stimulating hormone, promotes sperm and egg production LH = luteinizing hormone, estrogen and testosterone secretion from gonads (acts with FSH), ovulation ```
63
Secreting hormones
``` TSH = thyroid stimulating hormone, acts on thyroid, promotes TH secretion ACTH = adenocorticopic hormone, acts on adrenal cortex, promotes cortisol secretion ```
64
Prolactin
Non-tropic hormone | Acts on mammary glands (breast development, milk production)
65
Growth hormone (GH)
Causes liver to release IGFs (insulin-like growth factors, somatomedins) Stimulates protein synthesis and cell division (increased muscle, lengthening and thickening of bones)
66
Growth hormones other metabolic effects not related to growth
Increased fatty acids in blood (breakdown of fat stored in adipose tissue) Increased blood glucose (decreased glucose uptake by muscles)
67
Endocrine control of growth
Growth depends on growth hormone and on other factors = Genetics - maximum growth capacity Adequate diet and sleep Freedom from chronic disease and stress Normal levels of growth-influencing hormones (TH, insulin, epinephrine, androgens)
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Growth rate
Not continuous Fetal growth (promoted by hormones from placenta, GH plays no role) Postnatal growth spurt (first two years of life, GH controlled) Pubertal growth spurt (adolescence, GH)
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GH hyposecretion
Low GH Dwarfism (no genetic disease) Proportional growth
70
GH hypersecretion
Too much GH Before growth plates close = gigantism, lengthening of bones After growth plates close = acromegaly, thickening of bones instead
71
Pineal gland
Secretes melatonin = Influences body clock and antioxidant activity Other roles need research = SAD-seasonal affective disorder, sexual behaviour